Design of All-Solid Bandgap Fiber With Improved Confinement and Bend Losses

Abstract—We propose a new design of low-contrast all-solid bandgap fiber with low confinement and bend losses within low-order bandgaps. By introducing an index depressed layer around the high index rod in fiber cladding, we theoretically predict that the confinement loss of the proposed all-solid bandgap fiber would be significantly improved. Due to the enlarged index mismatch of the guided core mode and the edge of the bandgaps, the critical bend radius of the proposed fiber is remarkably reduced. Index Terms—Bend loss, confinement loss, photonic bandgap, photonic crystal fiber. I